Simulation and forecasting of inflow in the water source area of Danjiangkou reservoir based on the climate elasticity model

Using datasets of diurnal precipitation and temperature at 41 meteorological stations in the water source area of Danjiangkou reservoir as well as the inflow data from this reservoir during 1961-2015, we have analyzed the hydrometeorological characteristics in the water source area of this reservoir for establishing a climate elasticity fitting formula to simulate the inflow series, and then conducted forecasts for the future runoff evolution based on the estimations of precipitation and temperature under three emission scenarios of RCP2.6, RCP 4.5 and RCP 8.5. The results indicate that the temperature in the water source area exhibited a significantly upward trend at 0.13℃ per decade from 1961 to 2015, and its increase mainly appeared after 1990s'. There are clear interannual and interdecadal variations of inflow over the past 50 years, whose decreasing trend is overall 64.3 m³·s^-1 per decade. The variation tendency of inflow can commendably be simulated by the climate elasticity model, and the elasticity coefficient of runoff to precipitation is higher than to temperature. Both precipitation and temperature are in increasing trend and inflow shows different tendencies under the three emission scenarios of RCP2.6, RCP 4.5 and RCP 8.5. In RCP2.6 emissions scenario, the interdecadal inflows are in decreasing trend, whose decrement exceeded 270 m³·s^-1. In RCP4.5 emissions scenario, the interdecadal inflows all are in increasing trend. In RCP8.5 emissions scenario, the interannual inflows fluctuate severely and decrease by -14.2 m³·s^-1 per decade, which meant that it would not be favorable to the managing of water resources.